A few months ago, I decided to do something so unlike me that my friends were genuinely concerned: I decided to go to the gym. Regularly.

I mean, I don’t go to the gym. I take spin classes, do yoga and occasionally do one of those weird kitschy fitness classes that looks really cool on Snapchat. However, going from virtually never going to the gym to going practically every day is pretty hard on anyone’s body, and I spend most of my time being a mopey, sore person after a particularly grueling workout (looking at you, Flywheel.)

There’s a fine line between just being sore after a fitness session and feeling like something is inherently wrong. Once you cross over to the something is really wrong end of the spectrum, you become well acquainted with rhabdomyolysis — or what my CrossFit junkie friends fondly refer to as Uncle Rhabdo.”

Uncle Rhabdo isn’t that adorably bewildered uncle who brings you presents every time he visits. He’s the creepy uncle you want to avoid at all costs because he will probably fuck you up and then laugh about it when you cry.

You know you have rhabdo when your muscles virtually give out. It’s not just being tired or sore — it’s a matter of your body literally telling you that you can’t go on. Think not being able to bend your arms for days after an arm workout or extreme upper body swelling.

OK, so you’re probably thinking that it’s just like being a little too sore after a workout? No biggie, right? Not quite.

First off, it’s not just a matter of feeling extra sore. According to Healthline, your pee will be dark and almost like tea and you’ll feel sick. You might vomit, feel nauseous and just generally be irritable. If you wait too long to head to a doctor, you might even have seizures. Not your regularpost-gym muscle cramps, right?

Today, Shape Magazinereleased an interview with a woman who got rhabdomyolysis. She was neither extremely fit nor totally out of shape — she runs 20-30 miles weekly and does yoga and barre, which is healthier than most people.After a particularly tough upper body workout, she had to be hospitalized because — apart from feeling terrible and being swollen — her potassium levels were high enough to cause a heart attack.

She told Shape,

The doctors had to test my blood every four to six hours; they’d even wake me up during the night. They were testing levels of a muscle enzyme called CPK. The CPK level for a normal person should be between 10 to 120 IU/liter. I was admitted at 38,000 IU/liter.

Here’s the scariest part — if you don’t get treatment for rhabdo, you can die. Rhabdo causes your muscle tissue to break down and enter your bloodstream, which messes with your kidneys and they can just shut down. The only cure for it is hauling your ass to a hospital and having an IV in you depositing fluid into your system. For some people, treatment can take a few days and for some, a few weeks.

On a more positive note, the people most susceptible to rhabdo are people that are super fit to begin with, like CrossFitters. It doesn’t really happen to fitness beginners or people who have spent the past three years on their asses catching up on “Game of Thrones.”

So, basically, I’m good. And now I just gave you an excuse to never go to the gym again. Thank me later.